This invention relates to antimicrobial skin preparations. More specifically, it relates to PVP-I/alcohol preparations that are easy to apply but resist flow after application, are fast drying, and form water-resistant but easily removable films.
Antimicrobial skin preparations function to reduce skin infection in surgical and other wounds, including needle punctures. The application of antimicrobial preparations to wounds has become standard practice in hospitals, surgery centers, and medical test laboratories. This application is generally carried out through the use of swabs or sponges to deliver the liquid antimicrobial preparation to the skin. The preparations may be prepared for use in a pre-packaged form (i.e., liquid and swab in a sealed package) or as a separate bottled liquid. Multiple applications of antimicrobial skin preparations are often required, with the preparation either being allowed to dry or blotted dry between applications. Since most current antimicrobial skin preparations are water soluble, reapplication is often necessary after the wound is irrigated with water.
Antimicrobial skin preparations are well known in the art, including those containing iodine complexed with a polymer (iodophors). The polymer is most often polyvinyl pyrrolidone (Povidone). Iodophor preparations typically contain about 7.51-10% by volume of the iodine complex; Povidone-Iodine (PVP-I) solution is one of the most widely accepted preoperative antimicrobials. Solutions containing 5-10% PVP-I are generally recognized as safe. PVP-I solutions form a durable yet water soluble antimicrobial film when dry, and therefore resist pre-mature removal while permitting easy removal with water and mild rubbing. However, most existing iodophor skin preparations are low-viscosity liquids that tend to flow freely after application into areas remote from the wound site. This creates a need for extra care during application and increases the potential for irritation caused by solution pooling under the patient. A product that eliminates the flow problems associated with low-viscosity PVP-I solution is Povidone-Iodine gel (PVP-I gel). PVP-I gel is made by adding a cellulose gel, such as hydroxyethylcellulose, to PVP-I to greatly increase its viscosity to at least 8,000 cp. A PVP-I solution that is gelled with hydroxyethylcellulose is detailed in U.S. Pat. No. 5,137,718. In order to increase the initial kill of bacteria, alcohol can be added to PVP-I gel, as described in U.S. Pat. No. 5,916,882. Gelled PVP-I and PVP-I/alcohol solutions are flow-resistant compositions; however, as a result they are more difficult to dispense and apply than a low viscosity PVP-I solution. Furthermore, solutions in gel form dry slowly, which increases application time and reduces the benefits of the fast acting antimicrobial properties of alcohols in the PVP-I/alcohol gel. Another inherent problem with the current hydrophilic gel preparations is that they are water-soluble and therefore readily rehydrate during wound irrigation or subjection to water-containing body fluids, causing premature removal of the film and interference with surgical drape adhesion during surgical procedures.
Water-resistant films are disclosed in U.S. Pat. Nos. 6,228,354, 5,922,314 and 4,584,192, but the skin preparations that produce these films are low-viscosity and suffer from the flow/pooling problems discussed above. The PVP-I/alcohol solution disclosed in U.S. Pat. No. 6,228,354 has a faster drying time than the PVP-I/alcohol gel, thus taking full advantage of the fast acting antimicrobial properties of alcohol in conjunction with PVP-I. The solution further eliminates interference with surgical drape adhesion caused by gel, and has controlled moisture resistance thereby reducing the likelihood of premature removal by irrigation during procedures. However, in addition to its low viscosity, the film can only be removed with an aqueous alkaline solution and physical rubbing. Similarly, the composition of U.S. Pat. No. 4,584,192 is resistant to removal with water, and can only be removed by certain alcohols which irritate compromised skin.
Finally, most prior art antimicrobial skin preparations use water as a solvent, which slows their drying rate, resulting in slow film formation, flow away from the wound site, and lengthened application process time.
It would be beneficial to have an antimicrobial skin preparation combining the advantages of an antimicrobial agent and an alcohol, which preparation has sufficiently low viscosity for ease of dispensing and application, yet sufficiently high viscosity to cause the solution to remain in the area of the wound and not flow away or pool under the patient; which forms a water-resistant film that is difficult to remove during wound irrigation, but can be easily removed upon completion of the procedure; and which is fast drying so as to take advantage of the fast high initial kill properties of alcohol, limit flow away from the wound site, and decrease application time. Prior to this invention, no single product has been developed to combine the advantages of the various current antimicrobial skin preparations as discussed above.